N-type doped germanium contact resistance extraction and evaluation for advanced devices

The authors extract contact resistivity of NiGe layers on phosphorus-doped and arsenic-doped germanium, using the Transfer Length Method. It is shown experimentally that higher implant dose yields lower contact resistivity. Furthermore phosphorus is a better choice of dopant in terms of contact resistance and sheet resistance at low activation anneal temperatures, such as 500 °C. The impact of high contact resistance is evaluated for 22 nm technology NMOS germanium devices and beyond.